Internal combustion engine starting system in a hydraulic power transmission system

ABSTRACT

A hydraulic power transmission system comprising an internal combustion engine, at least a variable displacement axial plunger pump having a swash plate, and at least an axial plunger motor, is further provided with a starting pump, which is adapted to be operated directly manually, indirectly manually or by a load, for starting the internal combustion engine, when it does not properly start, in such a manner that the swash plate of the variable displacement axial plunger pump is hydraulically brought out of the neutral position by the action of the starting pump and then the internal combustion engine is driven by the load.

United States Patent Aoyama et al.

[1 1 3,654,758 [451 Apr. 11, 1972 INTERNAL COMBUSTION ENGINE STARTING SYSTEM IN A HYDRAULIC POWER TRANsMIssION SYSTEM Inventors: Ryozo Aoyama, Yokohama-shi; Akira Koiwai, Tokyo; Kenii Yamada, Kawasakishi,, Japan Assignee: Kabushiki Kaisha Komatsu Seisakusho (Komalsu Ltd.), Tokyo Filed: Dec. 1, 1969 Appl. No.: 881,161

Foreign Application Priority Data Dec. 4, 1968 Japan ..43/88310 Dec. 28, 1968 Japan .43/96075 US. Cl. ..60/19, 60/53 A, 123/179 F Int. Cl ,.F02n 7/00 Field of Search ..60/19, 18, 53 A, 14 B;

[56] References Cited UNITED STATES PATENTS 2,903,852 9/1959 Bottoms ..60/52 VS 3,085,403 4/ 1963 l-lamblin et a1 ..60/53 R 3,533,234 10/1970 Futamata et al..... ..60/19 2,838,908 6/ 1958 Forster ..60/18 3,411,297 11/1968 Harm ..60/53 A Primary Examiner-Edgar W. Geoghegan Attorney-Steinberg and Blake [57] ABSTRACT A hydraulic power transmission system comprising an internal combustion engine, at least a variable displacement axial plunger pump having a swash plate, and at least an axial plunger motor, is further provided with a starting pump, which is adapted to be operated directly manually, indirectly manually or by a load, for starting the internal combustion engine, when it does not properly start, in such a manner that the swash plate of the variable displacement axial plunger pump is hydraulically brought Out of the neutral position by the action of the starting pump and then the internal combustion engine is driven by the load.

4 Claims, 8 Drawing Figures INTERNAL COMBUSTION ENGINE STARTING SYSTEM IN A HYDRAULIC POWER TRANSMISSION SYSTEM This invention relates to an internal combustion engine starting system for a hydraulic power transmission system comprising an internal combustion engine, at least a variable displacement axial plunger pump having a swash plate, and at least an axial plunger motor.

In a known mechanical power transmission system which gears, belts and the like are used for power transmission, in case a starting means is in trouble or a battery has been discharged, the system is reversely driven by another machine or an inertial load so as to start the internal combustion engine. For example, in a car, in order to start an internal combustion engine of the car, which does not start properly, it is a common measure to move the car by another car. However, it is impossible to make such a measure for starting the internal combustion engine in a car provided with a hydraulic power transmission system. This fact is deemed to be a serious drawback of such a car.

For example, in a hydraulic power transmission system as shown in FIG. 1, there are an internal combustion engine 21, a variable displacement axial plunger pump 22, and a variable or invariable displacement axial plunger motor 23, of which the output shaft is connected with wheels of a car for driving the latter. The axial plunger pump 22 communicates with the axial plunger motor 23 by means of a pair of liquid conduits 24. A valve block 25 is arranged between and connected with the pair of liquid conduits 24 for protecting the liquid circuits by including a relief valve or the like therein. A fixed capacity pump 26 is driven by the internal combustion engine 21, of which the intake side is communicated with a liquid reservoir 28 through a filter 27 and the exhaust side communicates with the liquid conduits 24 through liquid lines 30 and 31, a pair of check valves 29 and 29, and a pair of liquid lines 32 and 32', respectively. There is a relief valve 33 which is set usually at a pressure as low as 3 to 20 kg./cm. for limiting the pressure of the pump 26 and returning surplus liquid medium to the liquid reservoir 28.

In order to vary the displacement of the variable displacement axial plunger pump 22 and/or the motor 23 depending upon the purpose of operation of the car, an appreciable magnitude of power is required, so that it is usual that a hydraulic servomechanism system is provided for varying the displace ment. The variable displacement axial plunger pump 22 is provided with a servomechanism 34. The variable or invariable displacement axial plunger motor 23 is provided with a servomechanism 35, which is connected with the other servomechanism 34 by a servoline 36. The displacement of the variable displacement axial plunger pump 22 may be directly or indirectly operated manually or through a mechanical, electrical or electromagnetical means. Such an operation for varying the displacement acts through the servomechanism 34 The hydraulic pressure for driving the servomechanism is, however, obtained from the fixed capacity pump 26 mechanically driven by the internal combustion engine 21, so that, when the latter is stopped, it is impossible to drive the pump 26, and therefore, the servomechanism system with the result that it is impossible to control the pump. The control of transmission of a hydraulically driven car is effected by combining variations of displacements of the axial plunger pump 22 and the motor 23, and therefore, the swash plate 41 (FIG. 3) of the variable displacement axial plunger pump 22 is normally brought into a neutral plane or position when the internal combustion engine 21 is stopped. Under these circumstances, it is impossible to operate the plate axial plunger pump 22 as a motor by driving it from the load through the axial plunger motor 23 or by the traction starting. In addition, when the axial plunger pump 22 is reversely driven up to an unusually high speed, such a serious trouble as seizure along sliding surfaces inside the pump can occur. Furthermore, disadvantageous occurrence of cavitation is also probable due to the pressure drop and excessively large flow at the low pressure side accompanied by an increase in the drainage caused by an unexpectedly large flow.

The primary object of this invention is to provide a hydraulic power transmission system comprising an internal combustion engine, a axial plunger pump, and a axial plunger motor, in which, even if the internal combustion engine is not started by its own starting system, it is possible to start the internal combustion engine by reversely driving it from the load.

Another object of this invention is to provide a hydraulic power transmission system comprising an internal combustion engine, an axial plunger pump having a swash plate, and an axial plunger motor, in which, even if the swash plate is stopped in its neutral position, it is possible to incline the swash plate directly manually 'or indirectly manually without operation of the internal combustion engine, for reversely starting the latter.

Still another object of this invention is to provide a hydraulic power transmission system comprising an internal combustion engine, an axial plunger pump, and an axial plunger motor, in which it is possible to reversely drive the internal combustion engine from a load through the axial plunger motor and the axial plunger pump without possibility of occurrence of such a trouble as seizure along sliding members and cavitation.

Briefly stated in accordance with one aspect of this invention, there is provided, in a hydraulic power transmission system comprising a prime mover such as an internal combustion engine, at least an axial plunger pump having a swash plate, and at least an axial plunger motor, an additional starting system for the internal combustion engine comprising another pump for hydraulically inclining the swash plate.

The invention will be better understood and other objects and additional advantages of the invention will become apparent upon perusal of the following description taken in connection with the drawings, in which:

FIG. 1 is a hydraulic circuit system of a hydraulic power transmission system in accordance with the prior art;

FIG. 2 is a hydraulic circuit system of an embodiment of a hydraulic power transmission system in accordance with this invention, in which the internal combustion engine, and therefore, the axial plunger pump are stopped;

FIG. 3 is an axially cross-sectional view of a variable displacement axial plunger pump shown in the same state as FIG. 2, and therefore, the swash plate is in its neutral position;

FIG. 4 is an enlarged view of an operating rod shown in FIG.

FIG. 5 is a cross-sectional view thereof taken along the line 55 of FIG. 4;

FIG. 6 is a cross-sectional view thereof taken along the line 6-6 of FIG. 4;

FIG. 7 is a hydraulic circuit diagram of another embodiment of a hydraulic power transmission system in accordance with this invention; and

FIG. 8 is a cross-sectional view of a starting pump united with axial plunger motor.

Similar numerals refer to similar parts throughout the several views.

While this invention is susceptible to embodiments in many different forms, there are shown in the drawings and will herein be described in detail two embodiments of the invention, with the understanding that the present disclosure is to be considered as exemplifications of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

Reference is now made to FIGS. 2 to 6, inclusive, illustrating an embodiment of this invention. The hydraulic power transmission system as shown in FIG. 2 is similar to the conventional one shown in FIG. 1, but further comprising an additional starting system for the internal combustion engine, comprising a starting pump 37 shown also in FIG. 3. The starting pump 37 is annexed to the variable displacement axial plunger pump 22 comprising a swash plate 41 (FIG. 3) pivoted to a pump casing. When the power of the internal combustion engine 21, is to be transmitted to the load through the axial plunger pump 22 and the axial plunger motor 23, the

swash plate 41 must be inclined from its neutral position. When the internal combustion engine 21 is stopped, the swash 41 of the plate axial plunger pump 22 is brought into the neutral position which is located in a plane perpendicular to the axis of the drive shaft of the pump 22. After positioning the swash plate 41 in the neutral position, in accordance with the prior art, it is impossible to incline the swash plate 41 without starting the internal combustion engine 21. Therefore, in this situation, it is impossible to transmit power in any direction through the axial plunger pump 22. That is, it is impossible to drive the internal combustion engine 21 from the load through the axial plunger motor 23 and the axial plunger pump 22. However, it is sometimes necessary to transmit power from the load to the internal combustion engine 21 because of a trouble in the starting system connected to the internal combustion engine 21 and for starting the latter without the action of the usual starting system but by virtue of reverse driving.

The starting pump 37 provided in accordance with this invention comprises a cylinder 38 integrated with the casing of the axial plunger pump 22. A piston 39 is adapted to be reciprocated in the cylinder 38. An arm of a piston rod 40 of the piston 39 is connected with a radial end 41a of the swash plate 41 through a link 42. The interior of the cylinder 38 is communicated with a change-over valve 43 through a pipe 44. The change-over valve 43 changes over two hydraulic circuits. One of the two hydraulic circuits is a draining circuit and the other is a charging circuit 44 for the starting pump 37, which communicates the recess of the starting pump 37 with a charging pump 45, having a cross-sectional inner area equal to that of the starting pump 37 for securing good responsive characteristics.

The charging pump 45 is controlled by an operating lever 50 which controls the change-over valve 43 also. An operating rod 49 is rotatably journalled by fixed members and operated by the operating lever 50 directly manually or indirectly intermediate a means such as mechanical, electrical or electromagnet means. A cam 53 protruded radially from the operating rod 49 is inserted inside a circumferential opening of a ring 48 having a connecting radial arm 55 linked with a piston rod 56 of the piston 45a adapted to be slidable inside a cylinder of the charging pump 45. The interior of the cylinder of the charging pump 45 is communicated with the changeover valve 43 and also with the reservoir 28 for the liquid medium through a check valve 54 so that the charging pump 45 is charged with the liquid medium from the reservoir 28 in the intake stroke and discharges the liquid medium to the change-over valve 43. Another ring 47 fixed to the operating rod 49 by means of a pin 52 is also formed with a connecting radial arm 57 linked with a valve rod 58 fixed to a spool of the change-over valve 43. Although the ring 47 is fixedly mounted on the operating rod 49, the ring 48 is circumferentially slidably mounted on the latter by the angle of the circumferential opening, which is angularly larger than the cam 53 by the clearance space 51 (FIG. for securing a time delay or lost motion for operating the change-over valve 43.

In operation, the operating lever 50 is turned directly or indirectly manually or by a means such as a mechanical, electrically or electromagnetical means. When the operating lever 50 is turned in the counterclockwise direction in FIGS. 5 and 6, the ring 47 is at first turned with the operating rod 49, and the valve rod 58 is pushed rightward operating the changeover valve 43 so that the charging pump 45 is brought into communication with the starting pump 37 through the pipes 44 and 46. When the changing over has been completed, the ring 48 is turned by the cam 53 of the operating rod 49 which is continuously turned in the counterclockwise direction in FIG. 5, and therefore, the piston 45a of the charging pump 45 is pushed rightward so that the liquid medium charged into the cylinder of the charging pump 45 from the reservoir 28 through the check valve 54 is pushed into the starting pump 37 through the pipes 46 and 44 and the changeover valve 43. By the action of the pressured liquid medium thus charged into the starting pump 37 the piston 39 thereof is pushed leftward in FIG. 5 so as to incline the swash plate 41. Upon inclination of the swash plate 41, it is possible to drive the internal combustion engine 21 from a load intermediate the axial plunger motor 23 and the plate axial plunger pump 22 in such a well known manner as so-called reverse driving for starting the internal combustion engine 21 without the action of its own starting system.

It is to be seen that, in the above-mentioned embodiment, it is possible to operate the change-over valve 43 and the charging pump 45 electromagnetically instead of mechanically as illustrated and described.

Reference is now made to FIGS. 7 and 8 illustrating another embodiment of this invention. There is a hydraulic transmission system similar to the conventional one shown in FIG. 1, but further comprises a starting system for the internal combustion engine 21, comprising a starting pump 137 as shown in FIGS. 7 and 8. The starting pump 137 is, for example, a reversible gear pump mechanically annexed to the variable displacement axial plunger motor 23. Normally a variable displacement axial plunger pump 22 is mechanically driven by an internal combustion engine 21. The variable displacement axial plunger motor 23 is hydraulically driven by the axial plunger pump 22 through a pair of liquid conduits 24 and 24' (FIG. 7). A load such as a car is mechanically driven by the axial plunger motor 23.

The variable displacement axial plunger motor 23 comprises a casing united with a front cover 136 and a rear cover 139 which serves also as a valve board. A cylinder block is arranged in front of the front surface of the rear cover 139 by a port plate 147. The cylinder block 145 is formed with a plurality of cylinders adapted to cooperate with a plurality of plungers 125, having heads held swingably by a swash plate 141, respectively. The swash plate 141 is swingably mounted on a pin 146 having an axis A and fixed to the casing 135. The plungers 125 are normally hydraulically driven by the axial plunger pump 22 by the liquid medium filled in the pair of liquid conduits 24 and 24' extended into an inlet 124 and an outlet 124' or vice versa. These inlet 124 and outlet 124 are communicated with the cylinders of the cylinder block 145 by the port plate 147 for distributing the hydraulic pressure, so as to reciprocate the plungers 125. By means of the above arrangement, the output of the axial plunger pump 22 is transmitted to the cylinder block 145. An output shaft 60 is arranged axially in the variable displacement axial plunger motor 23, which is connected with the cylinder block 145 so as to drive normally the output shaft 60 by the cylinder block 145. The front end 160 of the output shaft 60 is extended through the front cover 136 having a roller bearing 144 and a snap ring 127 for preventing leakage of the liquid medium, embedded in the front cover 136.

The rear end 142 of the output shaft 60 is extended through the port plate 147 and the rear cover 139 having a roller bearing 144 and a snap ring 126 for preventing leakage of the liquid medium, embedded in the rear cover 139, respectively, and a front case 152 of a gear chamber 148 of the gear pump 137. The front case 152 is secured to the rear cover 139 of the axial plunger motor 23 and constitutes a gear chamber 148 together with a rear case 153 and a side case 155. A driving gear is mounted on the extended rear end 142 of the output shaft 60 of the axial plunger motor 23 and in mesh with a driven gear 151 inside the gear chamber 148 provided with an liquid medium inlet and an liquid medium outlet (not shown in FIG. 8) so as to pump the liquid medium from the reservoir 28 to the liquid pressure servoline 36. The liquid medium inlet and the liquid medium outlet may be reversely used by rotating the starting pump 137 in the reverse direction. The liquid medium inlet and the liquid medium outlet are connected with the reservoir 28 by check valves 61 and 61', respectively, and also with the liquid pressure servoline 36 by check valves 62 and 62, respectively. These check valves 61 and 61 are arranged in opposition to the check valves 62 and 62', respectively. Numeral 149 denotes needle bearings. Numeral 154 denotes a key.

In operation, when the output shaft 60 of the plate axial plunger motor 23 is driven by a load when the internal combustion engine 21 has been stopped, for starting the latter in the manner of so-called reverse driving, the swash plate 41 (FIG. 3) of the axial plunger pump 22 is in its neutral position, and therefore, it is possible to rotate the axial plunger motor 23 and the starting pump 137 in either direction. However, it is impossible to drive the internal combustion engine 21 from the axial plunger pump 22 for starting the former. Under these circumstances, when the starting pump 137 is rotated, the liquid medium is charged from the reservoir 28 to the starting pump 137 through either of the two check valves 61 and 61' and exhausted from the starting pump 137 to the liquid pressure servoline 36 through either of the two check valves 62 and 62. The pressured liquid medium thus charged into the servomechanism 34 annexed to the variable displacement plate axial plunger pump 22, through the servoline 36, acts on the swash plate 41 so as to inline it out of its neutral position, and therefore, it is possible to drive the internal combustion engine 21 reversely from the load for starting the former.

As is apparent from the above description, the internal combustion engine 21 is operatively connected with the variable displacement pump means 22 in order to drive the latter. This pump means 22 has a drive shaft driven by the internal combustion engine, and the swash plate 41 is perpendicular to this drive shaft when this swash plate is in its neutral position. The servomechanism 34 is operatively connected with the swash plate 41 for determining the inclination thereof. The motor 23 forms a hydraulic motor means driven by the variable displacement pump means 22 and connected by way of the output shaft 60 to the wheels of the vehicle for propelling the latter. An adjusting pump means is provided for adjusting the inclination of the swash plate 41, and a drive means which is independent of the internal combustion engine is operatively connected to the adjusting pump means for driving the latter so as to incline the swash plate from its neutral position, thus enabling movement of the vehicle to cause the hydraulic motor means 23 to drive the variable displacement pump means 22 so that through the latter the engine can be started when its own starting system fails.

In the embodiment of FIGS. 2-6 the adjusting pump means includes the piston 45a driven by the rotary shaft 49 of the drive means which is independent of the internal combustion engine, and this shaft may be manually rotated as pointed out above. In addition the adjusting pump means of this embodiment includes the driven piston 39 operatively connected to the swash plate 41 and driven by the driving piston 45a of the adjusting pump means, in response to actuation of the valve means 43 which is also actuated from the rotary shaft 49.

In the embodiment of FIGS. 7 and 8 the gear pump 137 forms the adjusting pump means and acts through the servo mechanism 34 to adjust the inclination of swash plate 41.

While particular embodiments of this invention have been illustrated and described, modifications thereof will readily occur to those skilled in the art. It should be understood therefore that the invention is not limited to the two particular arrangements disclosed but that the appended claims are intended to cover all modifications which do not depart from the true spirit and scope of the invention.

What is claimed is:

I. For use with a vehicle having wheels which are driven in order to propel the vehicle, an internal combustion engine,

variable displacement pump means having a drive shaft operatively connected to said engine to be driven thereby and having a swash plate which in a neutral position is perpendicular to said drive shaft, a servomechanism operatively connected with said swash plate for determining the inclination thereof, hydraulic motor means for driving the wheels of the vehicle to propel the latter, said hydraulic motor means being operatively connected to said pump means to be driven thereby, adjusting pump means for adjusting the inclination of said swash plate independently of said servomechanism, and drive means independent of said internal combustion engine for driving said ad'ustin um means to incline said swash plate to an inclma on eren from its neutral position in order to start the internal combustion engine by moving the vehicle to drive said hydraulic motor means from the wheels of the vehicle and thus drive said variable displacement pump means from said hydraulic motor means to drive the internal combustion engine by said variable displacement pump means to start the engine when its own starting system fails, said adjusting pump means including a driving piston driven by said drive means and a driven piston operatively connected with said swash plate for adjusting the inclination thereof, and valve means for controlling communication between said driving and driven pistons of said adjusting pump means, said drive means including a rotary shaft operatively connected through a lost motion with said driving piston of said adjusting pump means and with said valve means for first operating the latter valve means and then said driving piston.

2. The combination of claim 1 and wherein a means is operatively connected with said rotary shaft for rotating the latter manually.

3. For use with a vehicle having wheels which are driven in order to propel the vehicle, an internal combustion engine, variable displacement pump means having a drive shaft operatively connected to said engine to be driven thereby and having a swash plate which in a neutral position is perpendicular to said drive shaft, a servomechanism operatively connected with said swash plate for determining the inclination thereof, hydraulic motor means for driving the wheels of the vehicle to propel the latter, said hydraulic motor means being operatively connected to said pump means to be driven thereby, adjusting pump means for adjusting the inclination of said swash plate independently of said servomechanism, and drive means independent of said internal combustion engine for driving said adjusting pump means to incline said swash plate to an inclination different from its neutral position in order to start the internal combustion engine by moving the vehicle to drive said hydraulic motor means from the wheels of the vehicle and thus drive said variable displacement pump means from said hydraulic motor means to drive the internal combustion engine by said variable displacement pump means to start the engine when its own starting system fails, said adjusting pump means being operatively connected with said servomechanism for acting through the latter on said swash plate to adjust the inclination thereof, said adjusting pump means being operatively connected directly to said hydraulic motor means to be driven thereby.

4. The combination of claim 3 and wherein said hydraulic motor means has an output shaft for driving the vehicle wheels, and said adjusting pump means being a gear pump having one gear connected directly to said output shaft to be driven by the latter. 

1. For use with a vehicle having wheels which are driven in order to propel the vehicle, an internal combustion engine, variable displacement pump means having a drive shaft operatively connected to said engine to be driven thereby and having a swash plate which in a neutral position is perpendicular to said drive shaft, a servomechanism operatively connected with said swash plate for determining the inclination thereof, hydraulic motor means for driving the wheels of the vehicle to propel the latter, said hydraulic motor means being operatively connected to said pump means to be driven thereby, adjusting pump means for adjusting the inclination of said swash plate independently of said servomechanism, and drive means independent of said internal combustion engine for driving said adjusting pump means to incline said swash plate to an inclination different from its neutral position in order to start the internal combustion engine by moving the vehicle to drive said hydraulic motor means from the wheels of the vehicle and thus drive said variable displacement pump means from said hydraulic motor means to drive the internal combustion engine by said variable displacement pump means to start the engine when its own starting system fails, said adjusting pump means including a driving piston driven by said drive means and a driven piston operatively connected with said swash plate for adjusting the inclination thereof, and valve means for controlling communication between said driving and driven pistons of said adjusting pump means, said drive means including a rotary shaft operatively connected through a lost motion with said driving piston of said adjusting pump means and with said valve means for first operating the latter valve means and then said driving piston.
 2. The combination of claim 1 and wherein a means is operatively connected with said rotary shaft for rotating the latter manually.
 3. For use with a vehicle having wheels which are driven in order to propel the vehicle, an internal combustion engine, variable displacement pump means having a drive shaft operatively connected to said engine to be driven thereby and having a swash plate which in a neutral position is perpendicular to said drive shaft, a servomechanism operatively connected with said swash plate for determining the inclination thereof, hydraulic motor means for driving the wheels of the vehicle to propel the latter, said hydraulic motor means being operatively connected to said pump means to be driven thereby, adjusting pump means for adjusting the inclination of said swash plate independently of said servomechanism, and drive means independent of said internal combustion engine for driving said adjusting pump means to incline said swash plate to an inclination different from its neutral position in order to start the internal combustion engine by moving the vehicle to drive said hydraulic motor means from the wheels of the vehicle and thus drive said variable displacement pump means from said hydraulic motor means to drive the internal combustion engine by said variable displacement pump means to start the engine when its own starting system fails, said adjusting pump means being operatively connected with said servomechanism for acting through the latter on said swash plate to adjust the inclination thereof, said adjusting pump means being operatively connected directly to said hydraulic motor means to be driven thereby.
 4. The combination of claim 3 and wherein said hydraulic motor means has an output shaft for driving the vehicle wheels, and said adjusting pump means being a gear pump having one gear connected directly to said output shaft to be driven by the latter. 